Add solution #60

Author: JoshCrozier

README.md

@@ -65,6 +65,7 @@
 57|[Insert Interval](./0057-insert-interval.js)|Medium|
 58|[Length of Last Word](./0058-length-of-last-word.js)|Easy|
 59|[Spiral Matrix II](./0059-spiral-matrix-ii.js)|Medium|
+60|[Permutation Sequence](./0060-permutation-sequence.js)|Hard|
 62|[Unique Paths](./0062-unique-paths.js)|Medium|
 64|[Minimum Path Sum](./0064-minimum-path-sum.js)|Medium|
 66|[Plus One](./0066-plus-one.js)|Easy|

solutions/0060-permutation-sequence.js

@@ -0,0 +1,43 @@
+/**
+ * 60. Permutation Sequence
+ * https://leetcode.com/problems/permutation-sequence/
+ * Difficulty: Hard
+ *
+ * The set [1, 2, 3, ..., n] contains a total of n! unique permutations.
+ *
+ * By listing and labeling all of the permutations in order, we get the
+ * following sequence for n = 3:
+ * - "123"
+ * - "132"
+ * - "213"
+ * - "231"
+ * - "312"
+ * - "321"
+ *
+ * Given n and k, return the kth permutation sequence.
+ */
+
+/**
+ * @param {number} n
+ * @param {number} k
+ * @return {string}
+ */
+var getPermutation = function(n, k) {
+  const factorial = [1];
+  for (let i = 1; i < n; i++) {
+    factorial[i] = factorial[i-1] * i;
+  }
+
+  const values = new Array(n).fill(0).map((_, i) => i + 1);
+  let result = '';
+  k--;
+
+  for (let i = n - 1; i >= 0; i--) {
+    const index = Math.floor(k / factorial[i]);
+    k = k % factorial[i];
+    result += values[index];
+    values.splice(index, 1);
+  }
+
+  return result;
+};